Will Climate Change Increase or Decrease the Number of Fish in the Sea?

Submitted by admin on 28 January 2009 - 10:59am

Principal Investigator(s):

Mary O'Connor

The answer to this question depends on several factors, most importantly on location, fishing pressure, and ocean temperature changes. Ocean temperature regimes are changing in many parts of the world, yet the overall effect of temperature on marine ecosystems, and specifically on fish production, is not well understood. For my research, I will assemble real data on fish catches, plankton abundance and sea surface temperature collected from ships in the Pacific and Atlantic oceans over the last 50 years. I will combine these data with theoretical and computer models to explore how warmer temperatures can cause fish and their plankton food to grow faster, eat more, and interact differently. I will also study how these changes can lead to bigger effects on fisheries harvests and biodiversity in different regions of the world.

Most marine animals have a life cycle in which the adults stay close to one place or habitat, and the babies travel in ocean currents to new habitats far from their parents. This journey is often 10's to 100's of miles, and most of the babies (or larvae) die on the way. Only a few make it to a new habitat where they can mature to adults. This kind of larval movement is very difficult to study, and is somewhat of a black box in our understanding of where baby animals go and where adults come from in the ocean. Because we don't know these details, it's often difficult to predict population size or stability from year to year, or place to place. We have discovered that the distance the babies travel is linked to ocean temperature, and this pattern is highly similar among nearly all types of marine animal. We can now link patterns of animal movement to ocean temperature, and try to understand population sizes and locations as ocean temperatures fluctuate over time.

Projected surface air temperature change by 2099, from the
Intergovernmental Panel on Climate Change (IPCC). Sea
Surface temperatures are closely linked to air temperatures.